Large oil-immersed transformer waste heat utilization method

Abstract

The invention belongs to the field of waste heat utilization, and relates to a large oil-immersed transformer waste heat utilization method.The waste heat utilization device comprises a heat exchange device and a waste heat absorption device, and one side of the heat exchange device communicates with an upper cooling branch mother pipe through a first heat exchange connecting pipeline and an electric three-way valve; the other side of the heat exchange device communicates with the waste heat absorption device through a second heat exchange connecting pipeline. A cooling variable-frequency oil pump is installed on the lower cooling branch mother pipe or the upper cooling branch mother pipe, a heat exchange variable-frequency oil pump is installed in the heat exchange device, frequency converters of the cooling variable-frequency oil pump and the heat exchange variable-frequency oil pump are installed in a control cabinet, and a CPU or an industrial personal computer is installed in the control cabinet. According to the temperature value in the oil tank, the temperature value in the pipeline and the oil flow value of the transformer, the opening degree of the electric three-way valve and the oil flow of the oil pump are automatically controlled and adjusted, so that the air cooling / self-cooling cooling device and the waste heat utilization device operate cooperatively. A large amount of energy is saved, and air heat pollution is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of waste heat utilization, and in particular relates to a waste heat utilization method of a large oil-immersed transformer based on a cooling mother pipe cooling structure. Background Art

[0002] At present, the world's energy development faces three major challenges: resource shortage, environmental pollution, and climate change. Most of the large amount of energy loss generated in power transportation is consumed in the form of heat energy. As an important heat-generating equipment in the operation of the power grid, transformers will generate a lot of losses in the iron core, windings, and steel structures due to the existence of resistance and magnetic resistance.

[0003] Generally, large oil-immersed transformers use self-cooling or air-cooling to cool the transformer oil, and the heat energy is dissipated into the surrounding air through the circulation cooling of the transformer oil. This not only wastes a lot of energy, but also causes air thermal pollution. Although the power conversion efficiency of large and medium-sized transformers has reached more than 99.5%, the energy lost is still considerable. In fact, from power generation, power supply to power consumption, it is generally necessary to use a transformer for three to four voltage transformations, and the loss is much greater. The larger the transformer capacity, the more heat energy is lost. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a method for utilizing waste heat of a large oil-immersed transformer based on a cooling mother pipe cooling structure. The technical solution adopted by the present invention is as follows: A method for utilizing waste heat of a large oil-immersed transformer, wherein the large oil-immersed transformer adopts a cooling mother pipe cooling structure, and air cooling / self-cooling cooling devices are symmetrically installed on both sides of the oil tank of the large oil-immersed transformer, and the air cooling / self-cooling cooling device comprises a lower cooling branch mother pipe and an upper cooling branch mother pipe; the method comprises the following steps: A waste heat utilization device connected to the air-cooling / self-cooling cooling device is installed, and the waste heat utilization device includes a heat exchange device and a waste heat absorption device. One side of the heat exchange device is connected to the upper cooling branch mother pipe through a heat exchange connection pipeline 1 and an electric three-way valve, and is connected to the lower part of the oil tank side wall of the large oil-immersed transformer through a heat exchange connection pipeline 1. The other side of the heat exchange device is connected to the waste heat absorption device through a heat exchange connection pipeline 2; A cooling variable frequency oil pump is installed on the lower cooling branch mother pipe or the upper cooling branch mother pipe, a heat exchange variable frequency oil pump is installed in the heat exchange device, and the frequency converter of the cooling variable frequency oil pump and the frequency converter of the heat exchange variable frequency oil pump are installed in a control cabinet; Temperature sensors and flow sensors are installed in all pipelines, an oil level temperature sensor is installed in the oil tank of a large oil-immersed transformer, a CPU or industrial computer is installed in the control cabinet, and all sensors are electrically connected to the CPU or industrial computer through data cables; According to the temperature value in the oil tank of the large oil-immersed transformer, the temperature value in the pipeline and the flow value in the pipeline, the opening of the electric three-way valve, the oil flow of the cooling variable frequency oil pump and the oil flow of the heat exchange variable frequency oil pump are automatically controlled by the CPU or industrial computer to make the air cooling / self-cooling cooling device and the waste heat utilization device operate in coordination, and the heat in the transformer oil is taken out and used in the waste heat absorption device.

[0005] Preferably, when the waste heat can be completely absorbed by the waste heat absorption device, the air cooling / self-cooling cooling device is cut off by the electric three-way valve, and the cooling variable frequency oil pump stops working; when the waste heat utilization device fails or is under maintenance, the waste heat utilization device is turned off and the waste heat of the transformer is released by the air cooling / self-cooling cooling device.

[0006] Preferably, the air-cooling / self-cooling cooling device includes a plurality of fan plates, the upper part of the fan plates is connected to the side wall of the upper cooling mother tube through an upper connecting pipeline, the upper cooling mother tube is connected to the top of the oil tank of the large oil-immersed transformer through a plurality of upper cooling branch mother tubes, the lower part of the fan plates is connected to the side wall of the lower cooling mother tube through a lower connecting pipeline, the lower cooling mother tube is connected to the lower part of the side of the oil tank of the large oil-immersed transformer through a plurality of lower cooling branch mother tubes, the upper cooling branch mother tube and the lower cooling branch mother tube are L-shaped bending structures, and the two ends of the upper cooling mother tube and the lower cooling mother tube are closed structures.

[0007] Preferably, the heat exchange device includes an oil-water heat exchanger, the heat exchange connecting pipeline includes an upper waste heat recovery branch pipe, an upper waste heat recovery mother pipe, a lower waste heat recovery mother pipe and a total waste heat recovery mother pipe with a bent structure, the upper cooling branch mother pipe includes an upper cooling longitudinal branch mother pipe and an upper cooling transverse branch mother pipe, an electric three-way valve is installed between the upper cooling longitudinal branch mother pipe and the upper cooling transverse branch mother pipe, the lower end of the upper cooling longitudinal branch mother pipe is connected to the top of the oil tank of the large oil-immersed transformer, and the upper end of the upper cooling longitudinal branch mother pipe is connected to the outlet of the electric three-way valve. The second outlet of the electric three-way valve is connected with the end of the upper cooling horizontal branch mother pipe, the third outlet of the electric three-way valve is connected with one end of the upper waste heat recovery branch pipe, the other end of the upper waste heat recovery branch pipe is connected with the side wall of the upper waste heat recovery mother pipe, one end of the upper waste heat recovery mother pipe is a closed structure, the other ends of the two upper waste heat recovery mother pipes are connected with one end of the total waste heat recovery mother pipe through a three-way pipe joint, the other end of the total waste heat recovery mother pipe is connected with the oil-water heat exchanger, one end of the lower waste heat recovery mother pipe is connected with the oil-water heat exchanger, and the other end of the lower waste heat recovery mother pipe is connected to the lower part of the side wall of the oil tank of the large oil-immersed transformer.

[0008] Preferably, the oil-water heat exchanger includes: an oil-side oil pump of the oil-water heat exchanger and an oil-side oil pump of the oil-water heat exchanger, the oil-side oil pump of the oil-water heat exchanger and the water-side oil pump of the oil-water heat exchanger are variable frequency oil pumps, and the frequency converters corresponding to the oil-side oil pump of the oil-water heat exchanger and the water-side oil pump of the oil-water heat exchanger are installed in a control cabinet.

[0009] Preferably, the waste heat disposal device includes a waste heat disposal pipeline, a heat pump and a terminal heat device. The water side of the oil-water heat exchanger is connected to one side of the heat pump, and the other side of the heat pump is connected to the terminal heat device through the waste heat disposal pipeline. The heat pump is equipped with a variable frequency oil pump on the terminal heat device side, and the frequency converter of the variable frequency oil pump on the terminal heat device side is installed in a control cabinet; by adjusting the frequency converter corresponding to the oil pump on the water side of the oil-water heat exchanger and the parameters of the heat pump, the water outlet temperature and flow rate of the heat pump are controlled to control the entire waste heat utilization device.

[0010] Preferably, the waste heat disposal device includes a temperature difference generator.

[0011] Preferably, the heat exchange device comprises an oil-oil heat exchanger, or other sealed heat exchange devices.

[0012] Beneficial effects of the present invention: The present invention transforms a large oil-immersed transformer based on a cooling mother tube cooling structure, adds a waste heat utilization device on the basis of the original air-cooling / self-cooling cooling device, saves a lot of energy, and avoids causing air thermal pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. Figure 1 This is the left view of a large oil-immersed transformer based on the cooling mother tube cooling structure; Figure 2 It is a top view of a large oil-immersed transformer based on a cooling mother pipe cooling structure; Figure 3 It is a left side view of the waste heat utilization system of the first embodiment of the present invention; Figure 4 is a top view of a waste heat utilization system according to a first embodiment of the present invention; Figure 5 is a partial enlarged view of the oil-water heat exchanger of the first embodiment of the present invention; Figure 6 1 is a schematic diagram of the structure of the electric three-way valve in the first embodiment of the present invention; In the figure, 1 is a large oil-immersed transformer, 2 is an air-cooled / self-cooled cooling device, 3 is a waste heat utilization device, 21 is an upper cooling mother pipe, 22 is an upper cooling branch mother pipe, 221 is an upper cooling longitudinal branch mother pipe, 222 is an upper cooling transverse branch mother pipe, 23 is a fan, 24 is a fan, 25 is a lower cooling mother pipe, 26 is a lower cooling branch mother pipe, 27 is a cooling variable frequency oil pump, 31 is an electric three-way valve, and 311 is an electric three-way valve outlet. , 312 is the second outlet of the electric three-way valve, 313 is the third outlet of the electric three-way valve, 32 is the upper waste heat recovery branch pipe, 33 is the upper waste heat recovery main pipe, 34 is the total waste heat recovery main pipe, 35 is the oil-water heat exchanger, 351 is the oil side oil pump of the oil-water heat exchanger, 352 is the water side oil pump of the oil-water heat exchanger, 36 is the lower waste heat recovery main pipe, 37 is the waste heat consumption device, 38 is the heat pump, 39 is the terminal heat-using equipment, and 40 is the control cabinet. DETAILED DESCRIPTION

[0014] The technical scheme of the present invention will be described clearly and completely in conjunction with the embodiments below. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] like Figure 1 , 2As shown, a method for utilizing waste heat of a large oil-immersed transformer is provided, wherein the large oil-immersed transformer 1 is based on a cooling mother pipe cooling structure, and air-cooling / self-cooling cooling devices 2 are symmetrically installed on both sides of the oil tank of the large oil-immersed transformer 1, and the air-cooling / self-cooling cooling device 2 comprises a plurality of slats 23, the upper part of the slats 23 is connected to the side wall of the upper cooling mother pipe 21 through an upper connecting pipeline, and the upper cooling mother pipe 21 is connected to the top of the oil tank of the large oil-immersed transformer 1 through a plurality of upper cooling branch mother pipes 22; the lower part of the slats 23 is connected to the side wall of the lower cooling mother pipe 25 through a lower connecting pipeline, and the lower cooling mother pipe 25 is connected to the side of the oil tank of the large oil-immersed transformer 1 through a plurality of lower cooling branch mother pipes 26. Among them, a fan 24 is provided in the air-cooling cooling device, and the fan 24 is fixedly installed at the bottom or side of the slats 23, and there is no fan in the self-cooling cooling device. The hot oil in the upper part of the oil tank of the large oil-immersed transformer 1 is collected into the upper cooling mother pipe 21 through the upper cooling branch mother pipe 22. The hot oil is dispersed from the upper cooling mother pipe 21 to the fan 23. The fan 24 is used to accelerate the air circulation of the fan 23 to improve the heat dissipation efficiency. After the hot oil is cooled in the fan 23, it flows through the lower cooling mother pipe 25 and the lower cooling branch mother pipe 26, and finally flows back to the oil tank of the large oil-immersed transformer 1, forming a complete transformer cooling system. The upper cooling branch mother pipe 22 and the lower cooling branch mother pipe 26 are L-shaped bending structures, and the upper cooling mother pipe 21 and the lower cooling mother pipe 25 are closed structures at both ends.

[0016] In the embodiment of the present invention, a method for utilizing waste heat of a large oil-immersed transformer is designed based on the large oil-immersed transformer 1 with a cooling mother pipe cooling structure having the above structure or a similar structure. Embodiment 1

[0017] In the first embodiment of the present invention, the existing cooling system of the large oil-immersed transformer 1 based on the cooling mother pipe cooling structure is technically transformed, and a waste heat utilization device 3 is added, so that the air-cooling / self-cooling cooling device 2 and the waste heat utilization device 3 can operate in coordination.

[0018] like Figure 3-6 As shown, first, a cooling variable frequency oil pump 27 is installed on the lower cooling branch mother pipe 26 of the air-cooling / self-cooling cooling device 2. In the first embodiment, the cooling variable frequency oil pump 27 is installed on the lower cooling branch mother pipe 26. Of course, the cooling variable frequency oil pump 27 can also be installed on the upper cooling branch mother pipe 22 as needed. The inverter of the cooling variable frequency oil pump 27 is installed in the control cabinet 40, and the cooling variable frequency oil pump 27 is controlled by the inverter, thereby controlling the oil flow of the air-cooling / self-cooling cooling device 2 and the waste heat utilization device 3.

[0019] The waste heat utilization device 3 includes a heat exchange device and a waste heat dissipation device 37. The heat exchange device includes an oil-water heat exchanger 35 and a heat exchange connecting pipeline. The heat exchange connecting pipeline includes an upper waste heat recovery branch pipe 32 and an upper waste heat recovery main pipe 33. In order to facilitate the installation of the oil-water heat exchanger 35, the upper cooling branch main pipe 22 is cut off at the bend, so that the original upper cooling branch main pipe 22 is divided into two sections, an upper cooling longitudinal branch main pipe 221 and an upper cooling transverse branch main pipe 222. An electric three-way valve 31 is installed between the upper cooling longitudinal branch main pipe 221 and the upper cooling transverse branch main pipe 222. The electric three-way valve 31 includes an electric three-way valve outlet 2 312 and an electric three-way valve outlet 3 313 symmetrical at both ends, and an electric three-way valve outlet 1 311 located between the electric three-way valve outlet 2 312 and the electric three-way valve outlet 3 313. The lower end of the upper cooling longitudinal branch mother pipe 221 is connected to the top of the oil tank of the large oil-immersed transformer 1, the upper end of the upper cooling longitudinal branch mother pipe 221 is connected to the electric three-way valve outlet 1 311, the electric three-way valve outlet 2 312 is connected to the end of the upper cooling transverse branch mother pipe 222, the electric three-way valve outlet 313 is connected to one end of the upper waste heat recovery branch pipe 32, the other end of the upper waste heat recovery branch pipe 32 is connected to the side wall of the upper waste heat recovery mother pipe 33, one end of the upper waste heat recovery mother pipe 33 is a closed structure, and the two ends are connected to the upper waste heat recovery mother pipe 33. The other end of the upper waste heat recovery mother pipe 33 is connected to one end of the total waste heat recovery mother pipe 34 through a three-way pipe joint, and the other end of the total waste heat recovery mother pipe 34 is connected to the oil-water heat exchanger 35. The total waste heat recovery mother pipe 34 is a bent structure, and one end of the lower waste heat recovery mother pipe 36 is connected to the oil-water heat exchanger 35, and the other end of the lower waste heat recovery mother pipe 36 is connected to the lower part of the oil tank side wall of the large oil-immersed transformer 1. After the hot oil is cooled in the oil-water heat exchanger 35, it flows back to the inside of the large oil-immersed transformer 1 through the lower waste heat recovery mother pipe 36.

[0020] The oil-water heat exchanger 35 includes: a heat exchange connecting pipeline, an oil-side oil pump 351 of the oil-water heat exchanger, and an oil-side oil pump 352 of the oil-water heat exchanger. The oil-side oil pump 351 of the oil-water heat exchanger and the oil-side oil pump 352 of the oil-water heat exchanger are variable frequency oil pumps, and the frequency converters corresponding to the oil-side oil pump 351 of the oil-water heat exchanger and the oil-side oil pump 352 of the oil-water heat exchanger are installed in the control cabinet 40. The oil-water heat exchanger 35 is an existing mature product, and the number and installation position of the oil-side oil pump 351 of the oil-water heat exchanger and the oil-side oil pump 352 of the oil-water heat exchanger can be flexibly set as needed. The characteristic of the oil-water heat exchanger 35 is that the transformer oil is cooled by cooling water, and the two oil-water cycles are relatively independent and will not cause oil-water mixing.

[0021] The waste heat disposal device 37 includes a waste heat disposal pipeline, a heat pump 38 and a terminal heat-using device 39. The oil side of the oil-water heat exchanger 35 is connected to the air-cooling / self-cooling cooling device 2, the water side of the oil-water heat exchanger 35 is connected to one side of the heat pump 38, and the other side of the heat pump 38 is connected to the terminal heat-using device 39. The heat pump 38 is equipped with a variable frequency oil pump on the side of the terminal heat-using device 39, and the frequency converter of the variable frequency oil pump on the side of the terminal heat-using device 39 is installed in the control cabinet 40. The heat pump 38 is an efficient energy-saving device that fully utilizes low-grade thermal energy. Heat can be spontaneously transferred from a high-temperature object to a low-temperature object, but cannot be spontaneously transferred in the opposite direction. The working principle of the heat pump 38 is a mechanical device that forces heat to flow from a low-temperature object to a high-temperature object in a reverse cycle. It consumes only a small amount of reverse cycle net work to obtain a large amount of heat supply, and can effectively utilize the low-grade thermal energy that is difficult to use to achieve energy saving. The heat pump 38 can transfer the heat energy of the low-level heat source to the high-level heat source for the terminal heat-using equipment 39, including but not limited to domestic hot water, winter heating, greenhouses, etc. For example, for heating, the heat pump 38 is used to convert the low-temperature heat source into a high-temperature heat source. At this time, one side of the heat pump 38 is connected to the oil-water heat exchanger 35, and the other side is connected to the heating pipeline. At this time, the heating pipeline is the terminal heat-using equipment 39, and the circulation on both sides is relatively independent; the heat pump 38 can absorb the heat of the cooling water coming out of the oil-water heat exchanger 35 and heat the circulating water of the heating pipeline on the other side. For example, the temperature of the cooling water coming out of the oil-water heat exchanger 35 is 50°C. The heat in the water can be absorbed by the heat pump 38, and together with the electric energy consumed by the heat pump 38 itself, it can be converted into the heat of the circulating water on the other side. The temperature of the circulating water in the heating pipeline can reach 80°C (the specific temperature is also determined according to the type of the heat pump 38, the needs of the terminal heat-using equipment 39, the water flow rate, etc.). The heat pump 38 can also utilize waste heat for refrigeration, replacing air conditioning for room cooling. This requires the selection of the heat pump 38 and also has requirements for the temperature of the water output by the oil-water heat exchanger 35 .

[0022] Furthermore, temperature, flow and other sensors are set in all pipelines, and an oil level temperature sensor is set in the oil tank of the large oil-immersed transformer 1. The sensors are electrically connected to the control cabinet 40 through data cables. At the same time, a transformer current signal light and a transformer voltage signal light are set in the control cabinet 40 to analyze the operation, heat dissipation, life of the transformer, and waste heat absorption, the coordinated operation of the air-cooling / self-cooling cooling device 2 and the waste heat utilization device 3, etc.

[0023] A plurality of frequency converters are installed in the control cabinet 40, and the frequency converters are matched with each frequency conversion oil pump to control the flow rate of each frequency conversion oil pump. The oil-water heat exchanger 35 and the waste heat dissipation device 37 are connected by two water pipes on the left and right to form a circulation pipeline. After the cooling water in the oil-water heat exchanger 35 cools the transformer oil, the cooling water takes out the heat in the transformer oil, and the temperature of the cooling water increases to high-temperature cooling water. The high-temperature cooling water enters the waste heat dissipation device 37, and after the waste heat is absorbed by the waste heat dissipation device 37, the temperature of the high-temperature cooling water drops to become low-temperature cooling water, and the low-temperature cooling water flows into the oil-water heat exchanger 35 again to cool the transformer oil. After the transformer oil is cooled, it will be re-input into the transformer oil tank. The heat absorbed by the waste heat dissipation device 37 determines the heat taken away by the oil-water heat exchanger 35, thereby determining the heat dissipated by the transformer through the oil-water heat exchanger 35. The entire system is flexibly controlled by the control cabinet 40, and a CPU or an industrial computer is installed in the control cabinet 40 to realize automatic control. The control method is a prior art.

[0024] At present, there is a technical gap in the utilization of transformer waste heat and the coordinated work with the existing transformer air cooling system. The present invention utilizes the waste heat of a large oil-immersed transformer. At the same time, the waste heat utilization and the original transformer air cooling system work together to ensure the maximum utilization of the waste heat while ensuring the normal heat dissipation of the transformer, thereby extending the service life of the transformer.

[0025] According to the analysis result of the CPU or industrial computer, the CPU or industrial computer controls the frequency converter and the electric three-way valve 31 to achieve the following functions: 1. When the waste heat of the transformer can be completely absorbed by the waste heat absorption device 37, the air cooling / self-cooling cooling device 2 is completely cut off through the electric three-way valve 31 (the electric three-way valve outlet 2 312 is closed, and the electric three-way valve outlet 3 313 is opened), the cooling variable frequency oil pump 27 stops working, and the waste heat of the transformer is completely absorbed by the waste heat utilization device 3.

[0026] 2. When the waste heat utilization device 3 fails or is under maintenance, the waste heat utilization device 3 can also be completely closed (the electric three-way valve outlet 2 312 is opened, and the electric three-way valve outlet 3 313 is closed), and the waste heat of the transformer is completely released by the air cooling / self-cooling cooling device 2, ensuring the normal operation of the transformer and the operating reliability of the transformer body.

[0027] 3. When the air-cooling / self-cooling cooling device 2 and the waste heat utilization device 3 need to work together, the electric three-way valve outlet 2 312 and the electric three-way valve outlet 3 313 are both opened, and the cooling frequency conversion oil pump 27 works. The channel size of the air-cooling / self-cooling cooling device 2 and the waste heat utilization device 3 can be adjusted by adjusting the opening angle of the electric three-way valve 31, and the frequency converter corresponding to the cooling frequency conversion oil pump 27 and the oil-water heat exchanger oil side oil pump 351 can be adjusted to adjust the pipeline flow, so as to achieve the purpose of reasonably dissipating the heat of the air-cooling / self-cooling cooling device 2 and the waste heat utilization device 3, and ensure that the waste heat of the transformer is fully utilized under the condition of normal heat dissipation of the transformer.

[0028] 4. The outlet water temperature and flow rate of the heat pump 38 can be controlled by adjusting the frequency converter corresponding to the water side oil pump 352 of the oil-water heat exchanger and the parameters of the heat pump 38. The entire waste heat utilization device 3 can be regulated by adjusting the difference between the required value and the actual value of the outlet water temperature and flow rate of the heat pump 38.

[0029] It is also possible to finely distribute the waste heat of large oil-immersed transformers based on the waste heat absorption at the rear end, so that the heat utilization rate of the transformer waste heat utilization device can be maximized. Embodiment 2

[0030] The waste heat disposal device 37 is not limited to the structure in the first embodiment, and waste heat utilization equipment such as a thermoelectric generator can also be used, or the heat pump 38, the terminal heat device 39 and the thermoelectric generator can be used in combination. The thermoelectric generator is a specific device that uses the thermocouple principle to directly convert thermal energy into electrical energy. The thermoelectric generator is a power generation device that uses the Seebeck effect to directly convert thermal energy into electrical energy. It is mainly composed of a combustion furnace, a power generation unit, a heat pipe and a cooling blade.

[0031] In specific applications, the thermoelectric generator is generally connected to a warm water pipe and a cold water pipe respectively. The transformer waste heat utilization device 3 can be connected to the warm water pipe, and water in the natural environment can be sent to the cold water pipe to realize the thermoelectric generator power generation. After power generation, the warm water of the waste heat utilization device 3 can be returned to the circulation according to the situation, or enter the heat pump 38 again, etc., which needs to be selected according to the specific application situation. Embodiment 3

[0032] In the heat exchange device, the oil-water heat exchanger 35 in Example 1 can also be replaced by a combination of a heat exchanger and an oil pump (oil-oil heat exchanger), or other sealable heat exchange devices, and the cooling medium water therein can also be replaced according to the situation, such as ethanol, a mixture of ethanol and water, etc.

[0033] In the embodiments of the present invention, technical features that are not described in detail are all existing technologies or conventional technical means and will not be described in detail here.

[0034] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them, and the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any technician familiar with the technical field can modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be covered within the protection scope of the present invention.

Claims

1. A method for utilizing waste heat of a large oil-immersed transformer, wherein the large oil-immersed transformer adopts a cooling mother pipe cooling structure, and air cooling / self-cooling cooling devices are symmetrically installed on both sides of the oil tank of the large oil-immersed transformer, and the air cooling / self-cooling cooling device comprises a lower cooling branch mother pipe and an upper cooling branch mother pipe; characterized in that: The following steps are involved: A waste heat utilization device connected to the air-cooling / self-cooling cooling device is installed, and the waste heat utilization device includes a heat exchange device and a waste heat absorption device. One side of the heat exchange device is connected to the upper cooling branch mother pipe through a heat exchange connection pipeline 1 and an electric three-way valve, and is connected to the lower part of the oil tank side wall of the large oil-immersed transformer through a heat exchange connection pipeline 1. The other side of the heat exchange device is connected to the waste heat absorption device through a heat exchange connection pipeline 2; A cooling variable frequency oil pump is installed on the lower cooling branch mother pipe or the upper cooling branch mother pipe, a heat exchange variable frequency oil pump is installed in the heat exchange device, and the frequency converter of the cooling variable frequency oil pump and the frequency converter of the heat exchange variable frequency oil pump are installed in a control cabinet; Temperature sensors and flow sensors are installed in all pipelines, an oil level temperature sensor is installed in the oil tank of a large oil-immersed transformer, a CPU or industrial computer is installed in the control cabinet, and all sensors are electrically connected to the CPU or industrial computer through data cables; According to the temperature value in the oil tank of the large oil-immersed transformer, the temperature value in the pipeline and the flow value in the pipeline, the opening of the electric three-way valve, the oil flow of the cooling variable frequency oil pump and the oil flow of the heat exchange variable frequency oil pump are automatically controlled by the CPU or industrial computer to make the air cooling / self-cooling cooling device and the waste heat utilization device operate in coordination, and the heat in the transformer oil is taken out and used in the waste heat absorption device.

2. The method for utilizing waste heat of a large oil-immersed transformer according to claim 1 is characterized in that: When the waste heat can be completely absorbed by the waste heat absorption device, the air cooling / self-cooling cooling device is cut off through the electric three-way valve, and the cooling variable frequency oil pump stops working; When the waste heat utilization device fails or is under maintenance, the waste heat utilization device is shut down and the waste heat of the transformer is released by the air cooling / self-cooling cooling device.

3. The method for utilizing waste heat of a large oil-immersed transformer according to claim 1 or 2, characterized in that: The air-cooling / self-cooling cooling device includes a plurality of fan blades, the upper part of the fan blades is connected to the side wall of the upper cooling mother tube through an upper connecting pipeline, the upper cooling mother tube is connected to the top of the oil tank of the large oil-immersed transformer through a plurality of upper cooling branch mother tubes, the lower part of the fan blades is connected to the side wall of the lower cooling mother tube through a lower connecting pipeline, the lower cooling mother tube is connected to the lower part of the side of the oil tank of the large oil-immersed transformer through a plurality of lower cooling branch mother tubes, the upper cooling branch mother tube and the lower cooling branch mother tube are L-shaped bending structures, and the upper cooling mother tube and the lower cooling mother tube are closed structures at both ends.

4. The method for utilizing waste heat of a large oil-immersed transformer according to claim 3 is characterized in that: The heat exchange device includes an oil-water heat exchanger, a heat exchange connecting pipeline includes an upper waste heat recovery branch pipe, an upper waste heat recovery mother pipe, a lower waste heat recovery mother pipe and a total waste heat recovery mother pipe with a bent structure, an upper cooling branch mother pipe includes an upper cooling longitudinal branch mother pipe and an upper cooling transverse branch mother pipe, an electric three-way valve is installed between the upper cooling longitudinal branch mother pipe and the upper cooling transverse branch mother pipe, the lower end of the upper cooling longitudinal branch mother pipe is connected to the top of the oil tank of the large oil-immersed transformer, and the upper end of the upper cooling longitudinal branch mother pipe is connected to the outlet of the electric three-way valve. The second outlet of the electric three-way valve is connected with the end of the upper cooling transverse branch mother pipe, the third outlet of the electric three-way valve is connected with one end of the upper waste heat recovery branch pipe, the other end of the upper waste heat recovery branch pipe is connected with the side wall of the upper waste heat recovery mother pipe, one end of the upper waste heat recovery mother pipe is a closed structure, the other ends of the two upper waste heat recovery mother pipes are connected with one end of the total waste heat recovery mother pipe through a three-way pipe joint, the other end of the total waste heat recovery mother pipe is connected to the oil-water heat exchanger, one end of the lower waste heat recovery mother pipe is connected to the oil-water heat exchanger, and the other end of the lower waste heat recovery mother pipe is connected to the lower part of the side wall of the oil tank of the large oil-immersed transformer.

5. The method for utilizing waste heat of a large oil-immersed transformer according to claim 4 is characterized in that: The oil-water heat exchanger comprises: an oil-side oil pump of the oil-water heat exchanger and an oil-side oil pump of the oil-water heat exchanger. The oil-side oil pump of the oil-water heat exchanger and the oil-side oil pump of the oil-water heat exchanger are variable frequency oil pumps. The frequency converters corresponding to the oil-side oil pump of the oil-water heat exchanger and the oil-side oil pump of the oil-water heat exchanger are installed in a control cabinet.

6. The method for utilizing waste heat of a large oil-immersed transformer according to claim 5, characterized in that: The waste heat disposal device includes a waste heat disposal pipeline, a heat pump and a terminal heat-using device. The water side of the oil-water heat exchanger is connected to one side of the heat pump, and the other side of the heat pump is connected to the terminal heat-using device through a waste heat disposal pipeline. The heat pump is equipped with a variable frequency oil pump on the terminal heat-using device side, and the frequency converter of the variable frequency oil pump on the terminal heat-using device side is installed in a control cabinet. By adjusting the frequency converter corresponding to the oil pump on the water side of the oil-water heat exchanger and the parameters of the heat pump, the water outlet temperature and flow rate of the heat pump are controlled to control the entire waste heat utilization device.

7. The method for utilizing waste heat of a large oil-immersed transformer according to claim 1 or 2, characterized in that: The waste heat disposal device includes a temperature difference generator.

8. The method for utilizing waste heat of a large oil-immersed transformer according to claim 1 or 2, characterized in that: The heat exchange device includes an oil-oil heat exchanger, or other sealed heat exchange devices.

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